These days, many types of devices (typically but not necessarily battery-powered) include an accelerometer or other inertial sensor (e.g., gyroscope) to perform various motion-based control functions in external devices (e.g., as an input to a video game system) and/or in the handheld device itself (e.g., motion-based orientation of displays, navigation of menus, data entry, etc.). Certain devices include motion-based power control functionality, such as transitioning into a “sleep” mode when the handheld device is stationary for some period of time in order to reduce power consumption or “waking up” upon detection of certain motion. In the “sleep” mode, certain circuitry is disabled or otherwise configured to reduce power consumption, although certain core functionality (such as the processor or portion of the processor needed for processing the accelerometer signals) generally remains powered and running in order to perform the accelerometer-based power control functions.
Generally speaking, the inertial sensor is coupled to a hardware-based processor that is configured to perform power control functions based at least in part on the signals generated by the inertial sensor. The hardware-based processor typically includes and/or controls various types of peripherals, such as a microprocessor core, a wireless transceiver (e.g., cellular, WiFi, etc.), a display (e.g., an LCD screen), various input-output devices, and other types of circuitry, and the processor can selectively manage these peripherals (and sometimes its own circuitry) to manage power consumption. For example, the processor may selectively turn off a display or the backlighting of the display, may turn off the wireless transceiver, may turn off some processor circuitry, etc.
In some devices, the inertial sensor and a related detection module may be powered on while the processor and its peripherals remain powered off, allowing for a limited amount of sensor-based functionality with substantial power savings. For example, United States Published Patent Application Nos. US2009/0240463, US2009/0293615, and US2009/0240462 (each of which is hereby incorporated herein by reference in its entirety) describe devices in which event capturing is triggered by a signal from a MEMS inertial sensor, such as for saving stored data or storing new data upon detection of a predetermined event. Here, the detection module may start to look for activity automatically at designated times, such as when the device is turned on or at periodic intervals thereafter.